Vehicle body levelling device for a working vehicle having outriggers

ABSTRACT

A vehicle body levelling device for a working vehicle having outriggers 5 provided at the front and rear of a self-propelled lower running body 1 for stabilizing the vehicle body while in service wherein the inclinations of the vehicle body in the front to rear and left to right directions thereof are detected by means of a front to rear inclination detector 13 and a left to right inclination detector 14, respectively, and the lengths of the front, rear, left and right outrigger arms 6 are detected by outrigger length detectors 18 so as to calculate by a controller 10 required amount of extension of piston rods of the left and right jack cylinders 7 provided on the front and rear outriggers 5, and wherein a control valve 15 provided on each of the jack cylinders is controlled in accordance with results of the calculation, whereby the vehicle body can be levelled in a short period of time even on an inclined place. The vehicle body levelling device further comprises a two-axis inclination detector 115 for detecting the inclinations in the front to rear and left to right directions of the vehicle body and hydraulic pressure detectors 117 provided on the respective jack cylinders 7, whereby extension/contraction amounts of the piston rods of the respective jack cylinders 7 are calculated by a controller 120 in accordance with the inclinations of the vehicle body detected by the two axis inclination detector 115 and an individual outrigger valve 111 provided on each of the jack cylinders 7 is controlled such that the hydraulic pressure of each of the jack cylinders 7 becomes a predetermined value, thereby making it possible to level the vehicle body in a short period of time only by operating an automatic levelling switch 121.

TECHNICAL FIELD

The present invention relates to a vehicle body levelling device for aworking vehicle having outriggers.

BACKGROUND TECHNOLOGY

In a working vehicle having outriggers for stabilizing a vehicle body ofa working vehicle such as a crane, it is necessary to maintain to levelthe vehicle body even on an inclined ground.

Accordingly, there is proposed a device for automatically levelling thevehicle body even on the inclined ground as disclosed in Japanese PatentPublication No. 2-30906.

However, when the vehicle body is levelled by the aforementionedconventional vehicle body levelling device for a working vehicle, it isnecessary firstly to extend each hydraulic jack unit to its maximum,then, to contract each hydraulic jack unit so as to level the vehiclebody in response to a signal issued by an inclination detector means,which causes such inconvenience that a working efficiency is loweredsince it takes time from the start of operation to the completion oflevelling of the vehicle body.

Further, since the conventional device starts the levelling control fromthe state where the hydraulic jack unit is in its maximum stroke tothereby lift the vehicle body to the maximum height, in ordinary case,the levelling control is frequently completed at the state where thevehicle body is lifted to its maximum.

As a result, the position of the center of gravity of the vehicle bodybecomes high, which makes the device unstable during the operationthereof.

The invention is made to improve such a drawback and to provide avehicle body levelling device for a working vehicle having outriggerswhich is capable of levelling the vehicle body in a short period oftime, and particularly to provide a vehicle body levelling device for aworking vehicle having outriggers which is capable of levelling thevehicle body in a position where the center of gravity of the vehiclebody is low.

DISCLOSURE OF THE INVENTION

To achieve the above objects, in a vehicle body levelling device for aworking vehicle having outriggers provided at the front and rear of aself-propelled lower running body according to a first aspect of theinvention, wherein the outriggers comprises outrigger arms which can beextended and contracted in the left and right directions thereof forstabilizing the vehicle body while in service, and jack cylindersprovided at distal ends of the outrigger arms for vertically supportingthe vehicle body, the vehicle body levelling device comprises a front torear inclination detector for detecting an inclination of the vehiclebody in the front to rear directions thereof, a left to rightinclination detector for detecting an inclination of the vehicle body inthe left to right directions thereof, outrigger length detectors fordetecting lengths of the outrigger arms, and a controller forcalculating whether the vehicle body is inclined in the front to rear orleft to right directions thereof, calculating extension/contractionamounts of piston rods, which are necessary for levelling the vehiclebody, of the jack cylinders provided on each outrigger arm, andcontrolling control valves provided on the jack cylinders in accordancewith results of calculation.

With such an arrangement, it is possible to level the vehicle body in ashort period of time even when the working vehicle operates on aninclined ground.

The vehicle body levelling device for a working vehicle havingoutriggers according to a second aspect of the invention furthercomprises a two-axis inclination detector for detecting inclinations ofthe vehicle body in the front to rear and left to right directionsthereof, hydraulic pressure detectors provided on the jack cylinders fordetecting hydraulic pressures in the jack cylinders, and a controllerfor calculating extension/contraction amounts of piston rods of the jackcylinders in accordance with inclinations of the vehicle body detectedby the two axis inclination detector and for controlling individualoutrigger valves provided on the jack cylinders such that hydraulicpressures of the jack cylinders become a predetermined value. Thevehicle body can be levelled in a short period of time by merelyoperating an automatic levelling switch.

With such an arrangement, it is possible to level the vehicle body in ashort period of time by merely operating an automatic levelling switchin the case of operating the vehicle body while the working vehiclestops on the inclined ground. Also, it is possible to improve stabilityof the vehicle body during the operation thereof since the vehicle bodyis levelled in a position where the center of gravity is low.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a working vehicle having outriggers accordingto an embodiment of the invention, FIG. 2 is a front view of the workingvehicle of FIG. 1, FIG. 3 is a block diagram of a vehicle body levellingdevice for the working vehicle of FIG. 1, FIG. 4 is a flow chart showingan operation of the vehicle body levelling device for the workingvehicle having outriggers of FIG. 3, and FIG. 5 is also a flow chartshowing an operation of the vehicle body levelling device for theworking vehicle of FIG. 3.

FIG. 6 is a side view of a working vehicle according to anotherembodiment of the invention, FIG. 7 is a front view of the workingvehicle of FIG. 6, FIG. 8 is a circuit diagram showing a hydrauliccircuit of outriggers of the working vehicle provided with a vehiclebody levelling device for the working vehicle of FIG. 6, FIG. 9 is ablock diagram showing a control system of the vehicle body levellingdevice, FIG. 10 is a block diagram showing a control system of a vehiclebody levelling device according to still another embodiment of theinvention.

FIGS. 11, 12 and 13 are flow charts showing operations of the vehiclebody levelling device.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the invention will be now described in detail withreference to FIGS. 1 to 5.

FIG. 1 shows a working vehicle having outriggers which includes aself-propelled lower running body 1, a freely turnable upper turningbody 2 provided on the lower running body 1, a crane boom 3 and anoperator's room 4 which are disposed on the upper turning body 2.

Outrigger 5 are provided on a vehicle body la of the lower running body1 at the front and rear thereof for stabilizing the vehicle body 1a. Theoutriggers 5 have outrigger arms 6 which can be extended and contractedsidewardly from the vehicle body 1a. Jack cylinders 7 each having apiston rod 7a projecting downward therefrom are vertically fixed to tipends of the outrigger arms 6. Floats 8 are swingably attached to tipends of the piston rods 7a (also refer to FIG. 2). The jack cylinders 7are controlled by a control unit as shown in FIG. 3 so that the pistonrods 7a can be extended or contracted.

The control unit comprises a controller 10 composed of a microcomputer.There are provided an automatic levelling switch 12, a front to rearinclination detector 13 for detecting the inclination of the vehiclebody 1a in the front to rear directions thereof, a left to rightinclination detector 14 for detecting the inclination of the vehiclebody 1a in the left to right directions thereof, and outrigger lengthdetectors 18 for detecting the lengths of the outrigger arms 6 providedat the front, rear, left and right of the vehicle body 1a, which arerespectively arranged at an input side of the controller 10. There areprovided control valves 15, which are respectively arranged at an outputside of the controller 10, for controlling the pressure of oil suppliedto each of the jack cylinders 7 of the outriggers 5. Each of the controlvalves 15 comprises a solenoid valve and it is connected to each of thejack cylinders 7.

An operation of the vehicle body levelling device will be now describedwith reference to a flow chart showing a levelling control program inFIG. 4. When the crane boom 3 is operated while the working vehiclestops on an inclined ground, the outrigger arms 6 are extended as longas possible so as to more stabilize the vehicle body 1a. Successively,four jack cylinders 7 are extended at the same time to such an extentthat tires float. In this state, the vehicle body 1a is inclined on theinclined ground.

Now, the automatic levelling switch 12 is turned on, whereby theprogram, i.e. levelling control program is started with a step 101.

The controller 10 checks whether a levelling flag is ON or not in a step102. If the levelling flag is ON, the controller 10 judges that theworking vehicle is levelled, whereby the vehicle body levelling controlis finished.

If the controller 10 judges that the levelling flag is not ON in thestep 102, the program goes to a step 103, wherein a levelling controlroutine is executed.

The levelling control routine is executed in accordance with a flowchart of FIG. 5. In a step 201, the controller 10 judges whether aninclination angle α of the vehicle body 1a in the front to reardirections thereof is less than, e. g, a∘ and also judges whether aninclination angle β of the vehicle body 1a in the left to fightdirections thereof is less than a∘. If the controller 10 judges that theinclination angles α and β are respectively greater than a∘, it sets anoperation time t₁ of each control valve 15, which is provided on eachjack cylinder 7, in a step 202, and operates each control valve 15 for aperiod of t₁ seconds in a step 203.

When the controller 10 judges that the inclination angles α and β arerespectively less than a∘, the program goes to a step 204, wherein thecontroller 10 judges whether the inclination angles α and β arerespectively less than b∘. If the controller 10 judges that theinclination angles α and β are greater than b∘, the program goes to astep 205, wherein the controller 10 sets an operation time t₂ of eachcontrol valve 15, which is shorter than the operation time t₁, andoperates each control valve 15 for a period of t₂ seconds in a step 206.When the inclination angles α and β are respectively less than b∘,namely, when the vehicle body 1a is levelled, the levelling flag is ON,whereby the levelling control is finished.

Whereupon, considering a case where the vehicle body 1a is not levelledeven if the piston rods 7a of the jack cylinders 7 are fully extendedwhen the inclination of the vehicle body is sharp, an interval timerstarts operation in a step 104. The interval timer adds up time duringthe levelling control routine in a step 105 while the controller 10checks whether the interval timer times out in a step 106. Thecontroller 10 continues the levelling control routine in case the timerdoes not time out.

If the controller 10 judges that the timer counts the time-out in thestep 106, the program goes to a step 107, wherein an alarm is operated.At the same time, the controller 10 stops the levelling control routine.

A vehicle body levelling device according to another embodiment of theinvention will be now described with reference to FIGS. 6 and 7.

FIG. 6 shows a working vehicle having outriggers which includes aself-propelled lower running body 1, a freely turnable upper turningbody 2 provided on the lower running body 1, a crane boom 3 and anoperator's room 4 which are disposed on the upper turning body 2, in thesame way as FIG. 1.

Outrigger 5 are provided on a vehicle body 1a of the lower running bodyI at the front and rear thereof for stabilizing the vehicle body 1a. Asshown in FIG. 7, the outriggers 5 have outrigger arms 6 which areextended and contracted sidewardly from the vehicle body 1a. Jackcylinders 7 each having a piston rod 7a projecting downward therefromare vertically fixed to tip ends of the outrigger arms 6. Floats 8 areswingably attached to tip ends of the piston rods 7a.

The outriggers 5 are generally called as an H-type outrigger. Thepresent invention can be also applied to an X-type outrigger havingoutrigger arms which are assembled in an X-shape.

FIG. 8 shows a hydraulic circuit of the outriggers 5. Hydraulic oildischarged by a hydraulic pump 119, when driven by an engine 118, isbranched off in two directions by an outrigger selector valve 110comprising a solenoid valve. One branched hydraulic oil is supplied tobottoms of arm slide cylinders 112 through individual outrigger valves111, each of which comprises a solenoid valve and is provided on each ofthe jack cylinders 7, and also it is supplied to heads of the jackcylinders 7 through double check valves 113. The other branchedhydraulic oil is supplied to heads of the arm slide cylinders 112.

As shown in FIG. 6, the vehicle body 1a has a two axial inclinationdetector 115 comprising a front to rear inclination detector 115a fordetecting the inclination of the vehicle body 1a in the front and reardirections thereof and a left to fight inclination detector 115b fordetecting the inclination of the vehicle body 1a in the left and rightdirections thereof. As shown in FIG. 7, the outriggers 5 have outriggerextension length detectors 116 for detecting the extension/contractionamounts of the outrigger arms 6 through wires 116a and the jackcylinders 7 have hydraulic pressure detectors 117 for detectinghydraulic pressures in bottom sides of the jack cylinders 7. Signalsdetected by these detectors 115, 116 and 117 are respectively input to acontroller 120 as shown in FIG. 9 and FIG. 10. The outrigger selectorvalves 110 and individual outrigger valves 111 are controlled as followsin response to these signals.

In FIGS. 9 and 10, denoted at 121 is an automatic levelling switch, 122is an alarm means for issuing a command from the controller 120, 123 isa display unit showing operating states of the outriggers 5.

An operation of the vehicle body levelling device using a control systemin FIG. 9 will be now described with reference to the flow chart of FIG.11. When the crane room 3 is operated while the working vehicle stops onthe inclined ground, the outrigger arms 6 are extended as long aspossible so as to stabilize the vehicle body.

When the automatic levelling switch 121 is turned on in this state, theprogram goes to a step 301, as illustrated in FIG. 11, wherein thecontroller 120 checks whether detectors, etc. are anomalous or not. Ifthe detectors, etc. are anomalous, the alarm means 122 issues an alarmsignal. On the other hand, if they are not anomalous, the program goesto a step 302, wherein the controller 120 checks whether both levellingand pressure flags are respectively ON or not.

If any or both of the levelling and pressure flags are not ON, theprogram goes to a step 303, wherein the controller 120 checks thepressure flag. If the pressure flag is not ON, the program goes to astep 304, wherein the controller 120 executes a pressure control routineas shown in FIG. 12. Thereafter, the program goes to a step 305, whereinthe controller 120 executes the levelling control routine as shown inFIG. 13.

If the pressure flag is ON in the step 303, the program goes to a step306, wherein the controller 120 executes the levelling control routine,then the program goes to a step 307, wherein the controller 120 executesthe pressure control routine, and finally it returns to the step 302,wherein the controller 120 checks whether both levelling and pressureflags are ON or not. If both levelling and pressure flags are ON, thecontroller 120 judges that the levelling of the vehicle body iscompleted and issues a control end indication to the display unit 123,so that the levelling control is finished.

The pressure control routine will be now described with reference toFIG. 12. The controller 120 judges whether hydraulic pressures of thefour jack cylinders 7 reach a set value by which tires float or not in astep 401. If the hydraulic pressures do not reach the set value, theprogram goes to a step 402, wherein the controller 120 operates theindividual outrigger valves 111 and outrigger selector valves 110 of thejack cylinders 7, hydraulic pressures of which do not reach the setvalue, for a period of time t₁ seconds so as to supply a short hydraulicpressure.

Thereafter, the program returns to the step 401, wherein the controller120 checks whether the hydraulic pressures reach the set value. If thehydraulic pressures reach the set value, the controller 120 permits thelevelling flag to be ON, and the program goes to a next step.

The controller 120 checks whether the hydraulic pressures of the jackcylinders 7 reach a relief set pressure or not in a step 403. If thehydraulic pressures of the jack cylinders 7 reach the relief setpressure, the controller 120 judges that the piston rods of the jackcylinders 7 reach stroke ends, and the program goes to steps 404 and405, wherein an alarm signal is issued by the alarm means 122, and thecontrol is finished.

The levelling control routine will be now described with reference toFIG. 13.

Suppose that the vehicle body 1a stops on the inclined ground. If thefront to rear inclination angle α is greater than 0, i.e., α>0, thevehicle body 1a is lifted at the front thereof. On the other hand, ifthe left to right inclination angle β is greater than 0, i.e., β>0, thevehicle body 1a is lifted at the left thereof.

Firstly, the controller 120 checks whether both absolute values of α andβ are less than the set value a∘ or not. If both absolute value of α andβ are not less than the set value a∘, the program goes to a step 502.

In the step 502, if the front to rear and left to right inclinations ofthe vehicle body 1a are expressed as the inclination angle α>0 and theinclination angle β>0, the controller 120 judges that the vehicle body1a is lifted at the front left thereof and operates a rear rightindividual outrigger valve 111 in response to the magnitude of theinclination angles α and β.

If both absolute values of α and β are less than the set value a∘ in thestep 501, the controller 120 permits the levelling flag to be ON, andthe program goes to a next step.

If the outrigger arms 6 extend long in the automatic levelling controloperation, the varied amount of the inclination angles of the vehiclebody 1a is small compared with a case where the outrigger arm 6 extendshort, provided that the jack cylinders 7 are operated for the sameinterval of time. As a result, it takes much time for positioning thevehicle body 1a to a precise levelling position.

In the control system as shown in FIG. 10, the detectors 116 fordetecting extension lengths of the outrigger arms are provided, whereinoperation times t_(j) of the individual outrigger valves 111 arecompensated in response to values detected by the detectors 116.

As a result, high accurate levelling control can be performed regardlessof the extension lengths of the outrigger arms 6.

When the hydraulic pressures of the jack cylinders 7 are detected at thebottom and head sides thereof, an axial force of each jack cylinder 7can be calculated based on the difference in area and pressure betweenthe bottom side of each jack cylinder 7 and the head side thereof,whereby the controller 120 can judge the float of the tire moreaccurately. As a result, the time to complete the pressure controlroutine can be reduced.

INDUSTRIAL UTILIZATION

As mentioned above in detail, necessary hydraulic oil is supplied fromthe control valves to the jack cylinders of the outriggers by merelyturning on the automatic levelling switch so that the vehicle body islevelled. As a result, the vehicle body can be fixed in a levelled statein a short time.

Accordingly, the working vehicle can start its operation quickly, whichleads to the improvement of the working efficiency. Further, since theprior art control valves can be used as they are, the vehicle bodylevelling device can be worked without changing the prior art deviceconsiderably, which makes it economical.

Since the vehicle body can be levelled as low as possible in itsposition, the center of gravity is lowered, which improves its stabilityduring the operation thereof. Further, the hydraulic oil necessary forlevelling the vehicle body is surely supplied to the jack cylinders, orthe hydraulic oil is supplied to the jack cylinders so as to generatenecessary axial force of the jack cylinders, so that the vehicle body isprevented from being stabilized due to the shortage of hydraulicpressure after the vehicle body is levelled or the shortage of the axialforce, or the vehicle body is prevented from being overturned.

Still further, since the extension lengths of the outrigger arms aredetected so as to compensate the operation times of the individualoutrigger valves, the vehicle body can be always levelled in a shortperiod of time even if the extension lengths of the outrigger arms aredifferentiated from one another on the ground where the working vehicleis located.

I claim:
 1. In a vehicle body levelling device for a working vehiclehaving outriggers provided at the front and rear of a self-propelledlower running body, said outriggers comprising outrigger arms which canbe extended and contracted in the left and right directions thereof forstabilizing said vehicle body while in service, and jack cylindershaving piston rods and provided at distal ends of said outrigger armsfor vertically supporting said vehicle body, said vehicle body levellingdevice comprises:a front to rear inclination detector for detecting aninclination of said vehicle body in the front to rear directionsthereof; a left to right inclination detector for detecting aninclination of said vehicle body in the left to right directionsthereof; outrigger length detectors for detecting lengths of saidoutrigger arms; and a controller for calculating extension/contractionamounts of said piston rods of said jack cylinders and controllingcontrol valves provided on said jack cylinders in accordance withresults of calculation.
 2. In a vehicle body levelling device for aworking vehicle having outriggers provided at the front and rear of aself-propelled lower running body, said outriggers comprising outriggerarms which can be extended and contracted in the left and rightdirections thereof for stabilizing said vehicle body while in service,and jack cylinders having piston rods and provided at distal ends ofsaid outrigger arms for vertically supporting said vehicle body, saidvehicle body levelling device comprises:a two-axis inclination detectorfor detecting inclinations of said vehicle body in the front to rear andleft to fight directions thereof; hydraulic pressure detectors providedon said jack cylinders for detecting hydraulic pressures in said jackcylinders; and a controller for calculating extension/contractionamounts of said piston rods of said jack cylinders in accordance withinclinations of said vehicle body detected by said two axis inclinationdetector and for controlling individual outrigger valves provided onsaid jack cylinders such that hydraulic pressures of said jack cylindersbecome a predetermined value.
 3. A vehicle body levelling deviceaccording to claim 2, further comprising outrigger extension lengthdetectors for detecting extension lengths of said outrigger arms,wherein operating times of said individual outrigger valves arecompensated in response to extension lengths detected by said extensionlength detectors.